configuring service provider for jndi lookup

[Terril Douglas]

Hello looking at the code snippet here:

Hashtable env = new Hashtable();
env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.fscontext.RefFSContextFactory");
env.put(Context.PROVIDER_URL, "file:/tmp/tutorial");
Context ctx = new InitialContext(env);

I am wondering for the env variables how do you know how to set up the service provider?

env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.fscontext.RefFSContextFactory");